Conventional vehicle battery cases are typically formed of plastic materials and include metal battery post terminals. Eventually the plastic case material weakens in the area about the terminals and no longer forms a good seal. Gases seep through the loose areas about the terminals, or through vents provided in the battery case and attack the terminals and connectors. As a result, the terminals and connectors become corroded and good electrical contact between connectors and terminals is lost.
A proven way to prevent corrosion is to hermetically isolate the contact areas between the terminals and connectors from the battery case. However, this has been a difficult task, especially as a "retrofit" with installed batteries. Covers which do form a relatively gas tight seal are expensive and difficult to install. Some such covers actually form an integral part of the battery terminal connector itself. Examples of present types of covers can be found in U.S. Pat. Nos. 2,800,522, 3,775,730 and 4,698,459.